Magnetic control device



NW7, 2% 1951 5 BKNFQRQ 2,5?6,56T.

MAGNETIC CONTROL DEVICE Filed May 18, 1949 2 SHEETS- SHEET l INVENTOR.

Patented Nov. 27, 1951 MAGNETIC CONTROL DEVICE Benjamin L. Binford, Chicago, IlL, assignor to Magnetrol, Inc., Chicago, 111., a corporation of Illinois Application May 18, 1949, Serial No. 93,937

11 Claims.

This invention relates to magnetic control devices and more particularly to devices for producing a movement of a magnetic control element by shifting a cooperating magnetic element in response to changes in a condition to be controlled.

Magnetic control devices have been Widely used to indicate or control various conditions such as liquid levels, pressures, and the like. Such de vices have generally been quite sensitive to small changes so that they operate through a relatively narrow control range and are apt to be unstable in rapidly fluctuating conditions or when subjected to vibration. These devices are furthermore diihcult to adjust and provide no adjustment for the control range.

It is one of the objects of the present invention to provide a magnetic control device having a relatively wide control range in order to decrease the sensitivity of the device. According to one feature of the invention the control range can easily be adjusted to change the sensitivity, as desired.

Another object is to provide a magnetic control device in which an actuating device such as a liquid displacer is connected to the movable magnetic element through a lost motion connection. Preferably, the lost motion connection is provided by adjustable stops engageable with the magnetic element to adjust the extent of the lost motion and accordingly the control range or sensitivity of the device.

Still another object is to provide a magnetic control device in which the actuating means comprises a plurality of spaced liquid displacers. The displacers are preferably adjustably mounted on an actuator rod to adjust the control range of the device.

A further object is to provide a magnetic control device in which the movable magnetic head is adjustably mounted relative to the supporting parts of the device to adjust the zero or neutral position. In the preferred construction a frame on which the head is supported is urged in one direction by a spring, and its movement in response to the spring is limited by an adjustable stop adj ustably to position the head.

The above and other objects and advantages of the invention will be more readily apparent when read in connection with the accompanying drawings, in which- Figure 1 is a vertical section with parts in elevation of a magnetic control device embodying the invention;

Figure 2 is apartial perspective view; and

Figure 3 is a view similar to Figure 1 alternative construction.

The device, as illustrated in Figure l, is adapted to be mounted in the upper surface of a tank or th like and to this end comprises a supporting plate it! to be mounted in horizontal position over an opening in the tank. The plate iii carries a vertical sleeve H which is threaded into a block 52 carrying a base 53 on which the magnetic parts are mounted. A tube it formed of non-magnetic material such as brass extends into the block l2 and-is sealed therein. The tube I4 is closed at it upper end a plug it which is threaded to receive a fastening stud IS.

The tube i 4 r .ceives a frame i? which is formed with openings in its opposite ends to fit slidably over the tube and which carries a terminal block 8 at one side. Leads to the terminal block may enter the base 13 through a nipple 19 to connect the terminal block to suitable indicating or control devices. Preferably, the frame I! i of nonmagnetic material to provide minimum interference with operation of the magnetic element. The frame is held in place by a spring 2i engaging its upper end and pr ssing its lower end against the base 13, the spring seating against a nut 22 threaded on the stud l6. The mechanism may be covered by a cover plate 23 fitting against the base i3 and held in place by a cap screw it on the end of the stud 55.

The frame ll movably carries a magnetic head which, as best seen in Figure 2, is formed by a permanent bar magnet 25 assembled with its opposite ends closely fitting against pole pieces 26 of magnetic material such as iron or steel. The pole pieces may be stampings which are held against the magnet by soldering or the like and also serve as a supporting frame for the magnetic head element. For this purpose the pole pieces carry a pivot pin 21 extending horizontally at the lower part of the head below its center of gravity and adjacent the horizontal position of it center of gravity. The pin 2i is journaled at its ends in the frame I i to support the head for pivotal movement about a horizontal axis below its center of gravity. With this construction the head tends to stay in either its upper or lower tilted position until it is moved by an outside force.

In the mounted position the ends of the pole pieces 25 are spaced apart and lie closely adjacent to opposite sides of the tube M. A back plate 22 is also secured to the head and carries an arm 28 on which is mounted a control device such as a tiltable mercury switch 3|.

To produce movement of the head, a magnetic of an armature and to raise the armature.

armature 32 is mounted within the tube for sliding movement therein. The armature is preferably in the form of an annular ring, and an actuating rod 33 extends loosely through the armature to move it.

According to one feature of the present invention the connection between the armature and the actuating rod is a loose or lost motion connection and is also preferably adjustable so that the extent of the lost motion and hence the sensitivity of the device may be adjusted. As shown, the rod 33 carries a pair of spaced nuts 34 threaded on the rod and of a size to engage the armature 32. By adjusting the spacing of the nuts the amount of travel of the rod before the armature will be moved can be adjusted as desired.

The actuator rod 33 is urged upward by a spring 35 housed in the sleeve II and engaging a block or collar 36 on the actuator rod. The collar 36 is threaded to receive an extension 3'! of the actuator rod which is adapted to project vertically downward into the tank and to be moved in response to changes in the liquid level in the tank.

In order further to increase the control range of the instrument and to provide an additional adjustment therefor the extension 31 of the actuator rod carries a pair of spaced liquid displacers 38 which are adjustably mounted on the rod by means of set screws 39. The displacers 38 may be spaced any desired distance and may be adjusted as required to satisfy the requirements of the particular installation.

In operation when the liquid level is low below the top of the lowermost displacer 38, the weight of the displacers will compress the spring 35 and move the armature 32 down to the position shown. At this time the magnetic head will be rocked counter-clockwise to open the mercury switch 3|.

As the liquid level rises above the lowermost displacer, the actuator rod will rise to some extent but will not move the armature 32 due to the lost motion connection between it and the rod. As the liquid level rises above the bottom of the top displacer 38, the rod will be elevated further to bring the bottom stop nut 34 into engagement with the As the armature moves up, the pole pieces 26 will follow it to tilt the carriage clockwise and close the switch 3|. This will effect a control operation such as the starting of a pump to remove liquid from the tank. As shown in the drawing, the armature 32 is loose in the tube [4 and the rod 33 is loose in the armature. Thus when the armature moves into the field of the magnet 25,'it will be attracted against the side of the tube and will be held frictionally and by magnetic attraction until the upper stop nut engages it and moves it down away from the magnet. Between the action of the spaced displacers and the lost motion connection, it will be seen that an extremely wide control range can be provided such, for example, as is desired in the operation of a sump pump so that the pump will not be started until a relatively high level is reached and will continue in operation until the level is very substantially reduced. By adjustment of the displacers and the stop nuts 34, the control range can easily be changed as desired.

Figure 3 illustrates an alternative construction, parts thereof which are identical with corresponding parts in Figure 1 being indicated by the same reference numerals. In this construction provisions are made for adjusting the normal or zero control point by shifting the frame 17 vertically on the tube 14. For this purpose a spring 41 is inserted below the frame ll urging the frame upward on the tube 4. Upward movement of the frame is limited by a sleeve 42 engaging a nut 43 threaded on an elongated stud 44 which is secured in the plug I5 at the top of the tube 14. Preferably the stud has a flat support 45 thereon which may be marked with suitable calibrations to indicate the adjustment. By adjusting the nut 43, the position of the frame I! on the tube can easily be changed to change the control point of the device easily and quickly. The mechanism is covered by a cover 46 which is preferably longer than the cover 43 of Figure 1 and which is held in place by a cap nut 41 threaded on the end of the stud 44. To provide access for adjustment, it is necessary only to remove the cap nut and the cover for access to the nut43.

As shown in Figure 3, the actuator rod extension 31 carries a single elongated displacer 48 to extend into the liquid in the tank. While this construction will not provide as wide a control range as the spaced displacers 38 of Figure 1, a substantial width of control range can nevertheless be obtained by separating the stop nuts 34 to a relatively wide degree thereby to provide a substantial lost motion between the actuator rod 33 and the armature '32. Other than the difference in the type of displacer employed and in the provision for adjustment of the control point, the construction of Figure 3 operates insubstantially the same way as that of Figure 1.

While two embodiments of the invention have been shown and described in detail herein, it will be understood that they are illustrative only and are not to be taken as a definition of the scope of the invention, reference being had for this pur pose to the appended claims.

What is claimed is:

1. A magnetic control device comprising a support having a non-magnetic wall portion, a head movably mounted on the support, a magnetic element on the head movable relative to said wall portion on one side thereof, a complementary magnetic element movably mounted on the other side of said wall portion, an elongated rod connected to the last named magnetic element to move it and adapted to extend into a liquid containing tank, a spring urging the rod in one direction and a pair of displacers connected to the rod at spaced points in its length to urge it in the frame, a magnetic element on the head m0v-r able relative to the wall portion at one side thereof, a complementary magnetic element movably mounted on the other side of the wall portion, and an actuating member connected to the last named magnetic element to move it.

3. A magnetic control device comprising a support having a vertically elongated non-magnetic wall portion, a frame mounted adjacent to the wall portion for vertical movement, a spring urging the frame in one direction, an adjustable stop adjustably limiting motion of the frame in response to the spring, ahead movably mounted on the frame, a magnetic element on the head movable relative to the wall portion at one side thereof, a complementary magnetic element movably mounted on the other side of the wall portion, an actuating member, and a lost motion connection between the last named magnetic element and the actuating member.

4. A magnetic control device comprising a support having a vertically elongated non-magnetic wall portion, a frame mounted adjacent to the wall portion for vertical movement, a spring urging the frame in one direction, an adjustable stop adjustably limiting motion of the frame in response to the spring, a head movably mounted on the frame, a magnetic element on the head movable relative to the wall portion at one side thereof, a complementary magnetic element movably mounted on the other side of the wall portion, an actuating rod, a lost motion connection between the rod and the last named magnetic element, a spring urging the rod in one direction, and liquid displacer means connected to the rod to urge it in the other direction.

5. A magnetic control device comprising a nonmagnetic tube, a head pivotally mounted adjacent to the tube, a magnetic pole piece on the head lying adjacent to the outside of the tube,

. a magnetic armature movable in the tube, an

actuating rod shiftable axially in the tube, spaced stop members on the rod spaced apart farther than the length of the armature to provide a lost motion connection between the rod and the armature, a spring urging the rod in one direction, and a pair of liquid displacers connected to the rod at spaced points to urge it in the other direction.

6. A magnetic control device comprising a nonmagnetic tube, a frame slidably mounted on the tube, a spring urging the frame in one direction, an adjustable stop adjustably limiting movement of the frame in said direction adjustably to position the frame relative to the tube, a head pivoted on the frame and having a magnetic pole piece lying adjacent to the tube, a magnetic armature movable in the tube, and actuating means connected to the armature to move it.

7. A magnetic control device comprising a nonmagnetic tube, a frame slidably mounted on the tube, a spring urging the frame in one direction, an adjustable stop adjustably limiting movement of the frame in said direction adjustably to position the frame relative to the tube, a head pivoted on the frame and having a magnetic pole piece lying adjacent to the tube, a magnetic armature movable in the tube, an actuating rod extending into the tube, adjustable stops on the rod engageable with the armature and spaced farther than the length of the armature to provide an adjustable lost motion connection, and an actuating device connected to the rod to move it.

8. A magnetic control device comprising a nonmagnetic tube, a non-magnetic frame fitting slidably over the tube, fastening means to secure the frame in place on the tube, a U-shaped magnetic head pivoted on the frame on an axis transverse to the tube length and having magnetic poles lying adjacent to the tube on opposite sides thereof, an annular magnetic armature fitting loosely in and movable in the tube, an actuating rod extending loosely through the armature, and stops on the rod engageable with the armature and spaced farther apart than the length of the armature to form a 10st motion connection between the rod and the armature.

9. A magnetic control device comprising a support having a non-magnetic wall portion, a head movably mounted on the support, a. magnetic element on the head movable relative to the Wall portion on one side thereof, a complementary magnetic element movably mounted on the other side of the magnetic wall portion, an elongated vertical rod, means forming a lost motion connection between the rod and the last named magnetic element, a spring urging the rod in one direction and a pair of displacers connected to the rod at spaced points in its length to urge it in the other direction.

10. The construction of claim 9 in which the head is pivoted on an axis below and horizontally adjacent to its center of gravity so that it tends to stay in any position to which it is tilted.

11. A magnetic control device comprising a non-magnetic vertical tube, a head pivoted on a horizontal axis adjacent to the tube and having magnetic pole pieces lying closely adjacent to the tube, the pivotal axis for the head lying below and horizontally adjacent to the center of gravity of the head, a magnetic armature movable in the tube, an actuating rod shiftable vertically in the tube, means forming a lost motion connection between the rod and the armature, and a pair of liquid displacers connected to the rod at spaced points.

BENJAMIN L. BINFORD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 706,505 Washington Aug. 5, 1902 1,193,744 Wilkinson Aug. 8, 1916 1,876,044 Davis Sept. 6, 1932 2,347,861 Winton May 2, 1944 2,425,691 Brewer Aug. 12, 1947 2,467,073 Binford Apr. 12, 1949 

